Carton sealing apparatus



Oct. 27, 1970 R. K. GELLATLY ETAL 3,535,848

CARTON SEALING APPARATUS Filed Oct. 17, 1968 v 4 Sheets-Sheet 1 ATTORNEYS Oct. 27,1970 R. K. GELLATLY ETAL 3,535,848

v CARTON SEALING APPARATUS I Filed Oct. 1?, 196a -4 Sheets-Sheet 2 S CIMLOV ANGIS L. HOFF BY New? E? ATTORNEYS Oct. 27, 1970 R. K. GELLATLY E-TAL 3,535,848

CARTON SEALING APPARATUS Filed Oct. 17, 1968 4'Sheets-Shee't s W NHL I B BY w: i. HI-F 1w, W

ATTORNEYS United States Patent 3,535,848 CARTON SEALING APPARATUS Robert K. Gellatly, Los Gatos, Boris Cimlov, Saratoga, and Francis L. Hoif, San Jose, Calif., assignors t0 FMC Corporation, San Jose, Calif., a corporation of Delaware Filed Oct. 17, 1968, Ser. No. 768,471 Int. Cl. B65b 51/10 US. Cl. 53-373 12 Claims ABSTRACT OF THE DISCLOSURE Apparatus for applying sealing pressure to a plurality of rows of cartons by cooperating toggle linkages connected to pivotal pressure applying sealing heads. One of the toggle linkages associated with each carton is moved to an overcenter locking position when in its sealing position, and the other toggle linkage is arranged to terminate its movement into sealed position prior to reaching said overcenter position. Resilient means are disposed in the actuating linkages to said toggle linkages thereby providing means for accommodating cartons having sealing flaps of different thicknesses.

Cross reference to related patents The carton sealing apparatus of the present invention is associated with the type of carton forming and filling machine disclosed in U.S. Pat. No. 3,248,841 which issued to Heifelfinger et al. on May 3, 1966 except that the machine is adapted to handle gable t'op cartons of the type disclosed in U.S. Pat. No. 3,207,049 which issued to Monroe et al. on Sept. 21, 1965.

Background of the invention Cartons which have a thermoplastic coating on their inside and outside surfaces are first heated to render the thermoplastic coating tacky, and the sealing surfaces are then forced together by pressure of about 850 p.s.i. for about two seconds by means of opposed sealing heads. In order to permit free entry of the top closure of the carton between the sealing heads, it is desirable that both heads be displaced from the sealing position as the carton is indexed therebetween, and that the heads thereafter be moved into clamping engagement with the top closure. Since both sealing heads are movable between a retracted position and a sealing position, it has been discovered that it is difiicult to prevent one head from overpowering the other head and thereby permitting slight displacement of the sealing surfaces of the top closure during the sealing operation.

Summary of the invention In accordance with the present invention it has been determined that by connecting the toggle linkages to the sealing heads in such a way that, while in the sealing position, one of the heads is moved to an overcenter locking position While the other head terminates its movement prior to reaching the overcenter locking position of its associated toggle linkage; that overpowering of one head by the other is prevented, that the carton will not shift during sealing thus providing an inferior seal, and that the power required to apply the sealing pressure is reduced to a minimum.

Brief description of the drawings FIG. 1 is a front elevation of the carton sealing apparatus of the present invention with parts broken away illustrating two rows of cartons with the toggle linkages and sealing heads associated with each row being disposed in sealing position.

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FIG. 2 is an enlarged side elevation looking in the direction of arrows 22 of FIG. 1 illustrating the general shape of the apparatus and further illustrating the power means and certain linkages for operating the sealing heads.

FIG. 3 is an enlarged section taken along lines 33 of 1 illustrating the toggle linkages in a retracted position.

FIG. 4 is an enlarged vertical section taken along lines 44 of FIG. 3 illustrating the central toggle linkage in sealing position with the central linkages moved to an overcenter lock position and further illustrating the outer linkages in their sealing positions short of their overcenter looking position.

FIG. 5 is a vertical section similar to FIG. 4 but illustrates the sealing heads in an open position.

Description of the preferred embodiment The carton sealing apparatus 10 (FIGS. 1 and 2) of the present invention is mounted on a frame 12 supporting a pair of intermittently driven conveyors 14 and 16. The conveyors include a series of upstanding pushers 18 having cartons C disposed therebetween. The top closure of each carton is of the well known gable type which includes two vertical sealing surfaces. The cartons are guided along their paths of movement by guide tracks 20 which are adjustably supported by vertical pedestals 22, 24 and 26 of the frame 12.

The frame 12 also includes an arch on beam 28 which is bolted to the upper end of pedestals 22 and 26 above the path of movement of the cartons. The arch 28 includes a forward wall 30 and rear wall 32 which are suitably bushed to provide pivotal support for pivot pins 34 of a central sealing head assembly 36 and two side sealing head assemblies 38 of similar construction.

As best illustrated in FIGS. 4 and 5, each side sealing assembly 38 includes a lever arm 40 and a sealing head 42 connected at their lower ends to adjacent pivot pins 34. A wide link 44 and a narrow link 46 are connected by pivot pins 48 to upper portions of the lever arm 40 and sealing head 42. The wide link 44 and narrow link 46 are connected together and to a yoke 50 by a central pivot pin 52 thereby defining a side toggle linkage.

The central sealing head assembly 36 is quite similar to the side sealing head assemblies 38. The central assembly 36 includes two sealing heads 56 and 58 connected at their lower ends to adjacent pivot pins 34. A wide link 60 is connected to the head 58 by a pivot pin 62, and a narrow link 64 is connected to the head 56 by a pivot pin 66. The two links 60 and 64 are connected together and to a yoke 68 by a pivot pin 70 to define a central toggle linkage. As illustrated in FIGS. 1 and 3, the pivot pins 52 and 70 have collars 72 'on their ends which project through and are guided during vertical movement by slots 73 in the forward and rear walls of the arch 28.

The toggle linkages are moved vertically between the positions illustrated in FIGS. 4 and 5 by hydraulic power unit 74 (FIGS. 1 and 2) which is actuated in timed relation with the movement of the conveyors 14 and 16 so as to raise and lower its piston rod 76 and a connecting link 78 when the conveyors have indexed cartons in two sealing stations. The upper end of the link 78 is pivotally connected to a lever 80 which is keyed to a pivot shaft 82 journaled on the frame 12. The lever is also pivotally connected to a second lever 84 by link 86 having a selfaligning connector on its lower end. The lever 84 is keyed to a cross shaft 87 journaled in the frame 12 and having three toggle linkage actuating levers 88, 90 and 92 keyed thereto. The free ends of each linkage actuating lever is forked and has a pivot pin 94 (FIGS. 3 and 4) journaled therein. Each pivot pin 94 is apertured to receive the threaded upper end of a link 96 which is pivotally connected to the associated yoke 50 or 68. A spring 98 or, if desired a plurality of resilient frusto-c'onical spring plates, are disposed between a fiat cut in the associated pin 94 and a collar 100 formed on the associated link 94 thereby providing a resilient connection between the pins 94 and the associated toggle linkages.

As illustrated in FIGS. 1, 4 and 5, a stop bolt 102 is locked to a web 104 of the frame 12 in position to positively limit downward movement of the central toggle linkage to a position slightly past the overcenter lock position of the linkage. Similarly, the stop bolts 106 are locked to webs 108 outwardly of the associated side toggle linkages in position to engage the associated wide link 44 when a carton is not in position to be sealed, and terminates movement of the toggle linkage 50 before the associated pin 52 moves past the overcenter lock position. The stop bolts 106 also prevent the sealing surfaces of adjacent sealing heads from contacting each other when a carton is not in sealing position.

In operation of the carton sealing apparatus 10 of the present invention, cartons C having the thermoplastic coating of their top closures heated to a bonding temperature are intermittently advanced by the conveyors 14 and 16 at about three second intervals into positions to be sealed. The power unit 74 is then actuated causing the free ends of the toggle linkage actuating levers 88, 90 and 92 to pivot downwardly to the position shown in FIG. 4 thereby causing the axis of the central pin 70 of the central toggle linkage to move downwardly to a plane A beyond the overcenter locking position, which position is defined by a horizontal plane B containing the pivot axes of the pins 62 and 66. The central toggle linkage is locked in the overcenter position by the stop bolt 102.

Downward movement of the side toggle linkage levers 88 and 92 cause the axes of the central pins 52 of the side toggle linkages to move downwardly to a position E above the overcenter locking position of the associated side toggle linkages, which overcenter locking position is defined by a plane D containing the axes of associated pins 48.

The connecting link 96 associated with the central toggle linkage is adjusted so that the central toggle linkage moves to its adjusted position slightly before the side toggle linkages move to their closing positions. In this way the central sealing head assembly 36 is locked in sealing position prior to the exertion of forces thereagainst by the side sealing assemblies 38 which would tend to overpower the central assembly. When cartons are in position to be sealed, the stop bolts 106 associated with the side sealing assemblies are ineffective and remain spaced from the assemblies. Downward pivotal movement of the toggle linkage levers 88, 90 and 92 continue until the desired sealing pressure is obtained, and differences in wall thicknesses of the top closure flaps of the cartons being sealed is accommodated by the springs 98. The total sealing pressure applied by the hydraulic power unit 74 may be adjusted to a predetermined pressure by means of a pressure regulator in the hydraulic system in a manner well known in the art.

In the specification and claims, it will be understood 4 that the term buckled position of the toggle linkage means that the linkage is position as illustrated in FIG. the term straight line position means that the three pivot axes of the toggle linkage lie in a common plane; and the term overcenter lock position means that the center pivot point of the toggle linkage has moved slightly beyond the above mentioned common plane as illustrated by the position of the central linkage in FIG. 4.

From the foregoing description it is apparent that the carton sealing apparatus includes at least two opposed sealing heads controlled by separate toggle linkages. In order to prevent overpowering of one of the sealing heads, one of the toggle linkages is moved to the overcenter locking position and the other toggle linkage is arranged so that its movement is terminated prior to reaching the overcenter locking position. Resilient means are also provided in the actuating means for the toggle linkages so as to accommodate cartons having top closures of different wall thicknesses.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention as set forth in the appended claims.

Having completed a detailed description of the inven tion so that those skilled in the art could practice the same, we claim:

1. A carton sealing apparatus for applying sealing pressure to the flaps of a carton to be sealed comprising means for supporting a carton at a sealing station, a pivotally mounted central sealing head having a sealing surface movable between a retracted position and a sealing position with said sealing surface engaging one side of the flaps of a carton to be sealed, a pivotally mounted side sealing head having a second sealing surface movable between a retracted position and a position wherein the second sealing surface engages the other side of the flaps to be sealed, a central toggle linkage pivotally connected to said central sealing head and movable between a buckled position and a substantially straight line position to move said central head between said retracted and said sealing position, a side toggle linkage pivotally connected to said side sealing head and movable between a buckled position and a substantially straight line position to move said side head between said retracted and said sealing positions, and means for actuating said toggle linkages.

2. An apparatus according to claim 1 wherein said central toggle linkage is moved past said straight line position into an overcenter lock position when said central sealing head is in sealing position.

3. An apparatus according to claim 2 wherein movement of the side toggle linkage into sealing position is terminated prior to the linkage reaching the straight line position.

4. An apparatus according to claim 3 wherein resilient means are connected between said actuating means and each of said toggle linkages so as to accommodate cartons having flaps which vary in thickness.

5. An apparatus according to claim 3 wherein said actuating means includes means for moving said central sealing head into sealing position prior to the movement of said side sealing head into sealing position.

6. An apparatus according to claim 2 wherein adjustable stop means are provided to terminate movement of said central toggle linkage in said overcenter locking position when said central sealing head is in its sealing position.

7. An apparatus according to claim 3 wherein adjustable stop means are provided to terminate movement of said side toggle linkage prior to reaching the straight line position.

8. An apparatus according to claim 3 wherein said supporting means is an intermittently driven conveyor.

9. A carton sealing apparatus for simultaneously applying sealing pressure to the flaps of two cartons, comprising a pair of spaced conveyors for supporting cartons and simultaneously moving two cartons into sealing stations, a pair of pivotally mounted central sealing heads having sealing surfaces movable into position to engage one side of the flaps of the two cartons being sealed, a pair of pivotally mounted side sealing heads each having a sealing surface movable into a position to engage the other sides of the flaps of the two cartons being sealed, a central toggle linkage pivotally connected to said central sealing heads and movable between a buckled position spacing said central heads from said flaps and sealing positions immediately adjacent a straight line toggle position urging the central heads against said side surfaces of the flaps of the two cartons, a pair of side toggle linkages with one linkage being connected to one of said side sealing heads and the other linkage being connected to the other side sealing head, each side toggle linkage being movable between a buckled position spacing said side head from the associated flaps to a sealing position immediately adjacent a straight line toggle position, and means for actuating said toggle linkages.

10. An apparatus according to claim 9 wherein said central toggle linkage is moved past said straight line position into an overcenter locking position when said central sealing heads are in sealing positions.

11. An apparatus according to claim 10 wherein movement of each side toggle linkage into sealing position is 12. An apparatus according to claim 10 wherein resilient means are connected between said actuating means and each of said toggle linkages so as to accommodate cartons having flaps which vary in thickness.

US. Cl. X.R.

straight line toggle positions. 

